GREENHOUSE GASES
Gases that trap heat in the atmosphere are called
greenhouse gases. This section provides information on
emissions and removals of the main greenhouse gases to
and from the atmosphere.
THREE GREENHOUSE GASES
Carbon dioxide (CO2)
Carbon dioxide enters the
atmosphere through burning
fossil fuels (coal, natural gas,
and oil), solid waste, trees
and other biological
materials, and also as a
result of certain chemical
reactions (e.g., cement
production). Carbon dioxide
is removed from the
atmosphere (or
"sequestered") when it is
absorbed by plants as part of
the biological carbon cycle.
Methane (CH4)
Nitrous oxide (N2O)
Nitrous oxide is emitted during
agricultural, land use, and industrial
activities; combustion of fossil fuels and
solid waste; as well as during treatment
of wastewater.
Methane is emitted
during the production
and transport of coal,
natural gas, and oil.
Methane emissions
also result from
livestock and other
agricultural practices,
land use, and by the
decay of organic
waste in municipal
solid waste landfills.
CLIMATE CHANGE
CLIMATE CHANGE IN THE PAST
Globally averaged air temperature at the Earth's surface has warmed by 1.1 °C since reliable records began in 1850. There is
no record of temperature having increased as rapidly as it has over the past century. Most of the hottest years on record
have occurred in the 21st century.
ICE AGE
THE FIRST ICE AGE EXPRIINCED
The Huronian glaciation is the oldest ice age we know about. The Earth was just over 2 billion years old, and home only to
unicellular life-forms. The early stages of the Huronian, from 2.4 to 2.3 billion years ago, seem to have been particularly
severe, with the entire planet frozen over in the first “snowball Earth”.
The Earth has cycled between relatively warm peroids realtivly cold ones in the warm peroids, there is no ice at all
even the poles. In the cold peroids , called ice agrs, there was ice at the poles
Snow ball earth
Snow
ball earth
on atleast one occasion perhaps 650 million years ago the whole earth was covered in ice nd snow
According to the snowball Earth hypothesis, for a long period of time, extending from 720
to about 630 Mya, the Neoproterozoic Earth experienced a freezing period during which a
thick layer of ice covered oceans and separated the Earth's atmosphere from the ocean.
This snowball Earth, also known as Cryogenian, resulted from a number of
glaciations, the last of which was the Marinoan glaciation that lasted from 660 to
630 Mya. The exhaustion of oxygen in the ocean might have led to the extinction of
algae and extremely low temperatures plausibly caused the extinction of the bulk of
preglacial microorganisms and plants.